1. Field of the Invention
This invention relates in general to pneumatic regulator valve assemblies and, more particularly, to a valve and regulator assembly having an automatic pressure release vent means.
2. Description of the Prior Art
The valve assembly of this invention finds application in pneumatically powered devices such as, for example, commercial vehicle windshield washers and other vehicle appliances operated pneumatically. Pressurized fluid to operate such devices is provided by compressed air obtained, for example, from the air supply tank used to supply air to operate the brakes on a commercial vehicle. When operating pneumatically powered devices such as a windshield washer from such a source, it is desirable that the pressure driving such pneumatically powered devices be kept fairly constant in order to maintain a uniformly predictable operating performance. Prior art systems provide a separate pressure regulator to control the flow of fluid to a separate 3-way valve. The 3-way valve in one position connects the pressure regulator output to a pneumatically driven windshield and in another position vents the windshield washer. A certain type of pneumatically driven windshield washer pump has a flexible diaphragm contained within a housing with a washing solution contained by the housing on one side of the diaphragm. This type of pump is operated by having air pressure applied against the other side of the diaphragm to force the washing solution out of the pump housing. When the air pressure is released, a reservoir supplies washing solution to refill the pump. Consequently, it is desirable that the air pressure be automatically relieved to permit the pump to be refilled. Providing the various required functions with separate assemblies results in an undesirably costly, large, bulky apparatus, particularly when mounted behind a crowded truck dash where space is at a premium. A control device for operating truck accessory equipment such as windshield washer pumps and the like should be as compact and functionally efficient as possible.